Service stations are comprised of a plurality of fuel dispensers that dispense fuel to motor vehicles A conventional exemplary fueling environment 10 is illustrated in FIGS. 1 and 2. Such a fueling environment 10 may comprise a central building 12, a car wash 14, and a plurality of fueling islands 16.
The central building 12 need not be centrally located within the fueling environment 10, but rather is the focus of the fueling environment 10, and may house a convenience store 18 and/or a quick serve restaurant (QSR) 20 therein. Both the convenience store 18 and the quick serve restaurant 20 may include a point-of-sale 22, 24, respectively. The central building 12 may further house a site controller (SC) 26, which in an exemplary embodiment may be the G-SITE® sold by Gilbarco Inc. of Greensboro, N.C. The site controller 26 may control the authorization of dispensing events and other conventional activities as is well understood. The site controller 26 may be incorporated into a point-of-sale, such as point of sale 22, if needed or desired. Further, the site controller 26 may have an off-site communication link 28 allowing communication with a remote location for credit/debit card authorization, content provision, reporting purposes or the like, as needed or desired. The off-site communication link 28 may be routed through the Public Switched Telephone Network (PSTN), the Internet, both, or the like, as needed or desired.
The car wash 14 may have a point-of-sale 30 associated therewith that communicates with the site controller 26 for inventory and/or sales purposes. The car wash 14 alternatively may be a stand-alone unit. Note that the car wash 14, the convenience store 18, and the quick serve restaurant 20 are all optional and need not be present in a given fueling environment.
The fueling islands 16 may have one or more fuel dispensers 32 positioned thereon. Each fuel dispenser 32 may have one or more fuel dispensing points. The term “dispensing point” can be used interchangeably with fuel dispenser 32 for the purposes of this application. A dispensing point 32 is a delivery point for fuel. The fuel dispensers 32 may be, for example, the ECLIPSE® or ENCORE®) sold by Gilbarco Inc. of Greensboro, N.C. The fuel dispensers 32 are in electronic communication with the site controller 26 through a LAN or the like.
The fueling environment 10 also has one or more underground storage tanks 34 adapted to hold fuel therein. As such, the underground storage tank 34 may be a double-walled tank. Further, each underground storage tank 34 may include a liquid level sensor or other sensor 35 positioned therein. The sensors 35 may report to a tank monitor (TM) 36 associated therewith. The tank monitor 36 may communicate with the fuel dispensers 32 (either through the site controller 26 or directly, as needed or desired) to determine amounts of fuel dispensed, and compare fuel dispensed to current levels of fuel within the underground storage tanks 34 to determine if the underground storage tanks 34 are leaking. In a typical installation, the tank monitor 36 is also positioned in the central building 12, and may be proximate to the site controller 26.
The tank monitor 36 may communicate with the site controller 26 and further may have an off-site communication link 38 for leak detection reporting, inventory reporting, or the like, which may take the form of a PSTN, the Internet, both, or the like. As used herein, the tank monitor 36 and the site controller 26 are site communicators to the extent that they allow off-site communication and report site data to a remote location. The site controller 26 and the tank monitor 36 are typically two separate devices in a service station environment.
In addition to the various conventional communication links between the elements of the fueling environment 10, there are conventional fluid connections to distribute fuel about the fueling environment as illustrated in FIG. 2. The underground storage tanks 34 may each be associated with a vent 40 that allows over-pressurized tanks to relieve pressure thereby. A pressure valve (not shown) is placed on the outlet side of each vent 40 to open to atmosphere when the underground storage tank 34 reaches a predetermined pressure threshold. Additionally, under-pressurized tanks may draw air in through the vents 40. In an exemplary embodiment, two underground storage tanks 34 exist—one a low octane tank (87 grade for example) and one a high octane tank (93 grade for example) Blending may be performed within the fuel dispensers 32, as is well understood, to achieve an intermediate grade of fuel. Alternatively, additional underground storage tanks 34 may be provided for diesel and/or an intermediate grade of fuel (not shown).
Pipes 42 connect the underground storage tanks 34 to the fuel dispensers 32. Pipes 42 may be arranged in a main conduit 44 and branch conduit 46 configuration, where the main conduit 44 carries the fuel that is pumped by a fuel pump, such as a submersible turbine pump (not shown) for example, from the underground storage tanks 34 to the branch conduits 46, and the branch conduits 46 connect to the fuel dispensers 32. Typically, the pipes 42 are double-walled pipes comprising an inner conduit and an outer conduit. Fuel flows in the inner conduit to the fuel dispensers, and the outer conduit insulates the environment from leaks in the inner conduit. For a better explanation of such pipes and concerns about how they are connected, reference is made to Chapter B13 of PIPING HANDBOOK, 7th edition, copyright 2000, published by McGraw-Hill, which is hereby incorporated by reference.
As better illustrated in FIG. 3, each fuel dispenser 32 is coupled to a branch conduit 46 to receive fuel from the underground storage tank 34 via the main conduit 44. The fuel dispenser 32 is coupled to a branch conduit 46 that is coupled to the main conduit 44 to receive fuel As fuel enters into the fuel dispenser 32 via the branch conduit 46, the fuel typically first encounters a shear valve 48. The shear valve 48 is designed to cut off the fuel delivery piping 47 internal to the fuel dispenser 32 from the branch conduit 46 in the event that an impact is made on the fuel dispenser 32 for safety reasons. The fuel delivery piping 47 carries the fuel inside the fuel dispenser 32 to its various components before being delivered to a vehicle. As is well known in the fuel dispensing industry, the shear valve 48 is designed to shut off the supply of fuel from the underground storage tank 34 and the branch conduit 46 if the fuel dispenser 32 is impacted to ensure that any damaged internal fuel supply piping 47 due to an impact cannot continue to receive fuel from the branch conduit 46 that may then be leaked to the ground, the customer, and/or the environment.
After the fuel leaves the shear valve 48, the fuel typically passes through a flow control valve 49 located inline to the fuel supply piping 47. The flow control valve 49 may be used to control the flow of fuel into the fuel dispenser 32. The flow control valve 49 may be a two stage valve so that the fuel dispenser 32 controls the flow of fuel in a slow mode at the beginning of a dispensing event and at the end of the transaction (in the case of a prepaid fuel transaction), and a fast mode for fueling during steady state after slow flow mode is completed.
After the fuel leaves the flow control valve 49 in the fuel supply piping 47, the fuel may encounter a filter 50 to filter out any contaminants in the fuel before the fuel reaches the flow meter 52 that is typically located on the outlet side of the filter 50. The filter 50 helps to prevent contaminates from passing to the fuel flow meter 52 and the customer's fuel tank. Contaminates can cause a fuel flow meter 52 to malfunction and/or become un-calibrated if the meter 52 is a positive displacement meter, since the contaminate can scrub the internal housing of the meter 52 and increase the volume of the meter 52. If a filter 50 becomes clogged or blocked in any way, either wholly or partially, this will impede the flow of fuel from the fuel dispenser 32 and thereby reduce the maximum throughput/flow rate of the fuel dispenser 32. The maximum throughput of the fuel dispenser 32 is the maximum flow rate at which the fuel dispenser 32 can deliver fuel to a vehicle if no blockages or performance problems exist.
The filter 50 is changed periodically by service personnel during service visits, and is typically replaced at periodic intervals or when a fuel dispenser 32 is noticeably not delivering fuel at a fast enough flow rate. Because the filter 50 is changed in this manner, a fuel dispenser 32 may encounter unusual and unintended low flow rates for a period of time before they are noticed by the station operators and/or before service personnel replace such filters 50 during periodic service visits. There are also other components of a fuel dispenser 32 in addition to the filter 50 than may cause a fuel dispenser 32 to not deliver fuel at the intended flow rate, such as a defective or blocked valve 48, meter 52, hose 58, nozzle 60, or any other component in the fuel supply line 47 of the fuel dispenser 32.
After the fuel leaves the filter 50, the fuel enters into the fuel flow meter 52 to measure the amount of volumetric flow of fuel. The amount of volumetric flow of fuel is communicated to a controller 54 in the fuel dispenser 32 via a pulse signal line 56 from the fuel flow meter 52. The controller 54 typically transforms the pulses from the pulse signal line 56 into the total number of gallons dispensed and the total dollar amount charged to the customer, which is then typically displayed on LCD displays (not shown) on the fuel dispenser 32 visible to the customer. Note that the flow control valve 49 discussed above may be located on either the inlet or outlet side of the fuel flow meter 52.
After the fuel leaves the fuel flow meter 52, the fuel is delivered to the fuel supply piping 47 on the outlet side of the fuel flow meter 52 where it then reaches a hose 58. The hose 58 is coupled to a nozzle 60. The customer controls the flow of fuel from the hose 58 and nozzle 60 by engaging a nozzle handle (not shown) on the nozzle 60 as is well known.
If there is any blockage, either partially or wholly, in the fuel supply piping 47 within the fuel dispenser 32 or any components located inline to the fuel supply piping 47, the fuel cannot be delivered by the fuel dispenser 32 to a vehicle at the maximum throughput or flow rate that the fuel dispenser 32 would be capable of performing if no blockage existed. A blockage in the fuel supply piping 47 can occur within the piping 47 itself or as a result of a blockage in any of the components that are located inline to the fuel supply piping 47, including but not limited to the shear valve 48, the flow control valve 49, the filter 50, the fuel flow meter 52, the hose 58, and the nozzle 60. Also, if the submersible turbine pump that pumps fuel from the underground storage tank 34 to the fuel dispensers 32 is suffering from reduced performance and/or pumping rate, this may result in fuel dispensers 32 not delivering the maximum throughput or flow rate of fuel.
Any decline in the submersible turbine pump performance, a blockage in the fuel supply piping 47, or a blockage in components located inline to the fuel supply piping 47 may cause the fuel dispenser 32 to either not deliver fuel at all or at a reduced rate, thereby reducing the throughput efficiency of the fuel dispenser 32 and possibly requiring a customer to spend more time refueling a vehicle. The customer may be frustrated and therefore not visit the same service station for his or her fueling needs. The reduced throughput of the fuel dispenser 32 may also cause other customers to wait longer for a fueling position thereby resulting in lost revenue in terms of lost opportunity revenues. If the fuel dispenser 32 throughput efficiency can be measured and then compared against a normal throughput in an automated manner, fuel dispenser 32 throughput problems can be detected shortly after their occurrence to allow a station operator and/or service personnel to remedy the problem more quickly.
Until the present invention, one method known for monitoring the throughput efficiency of a fuel dispenser 32 is to calculate the flow rate of the fuel dispenser 32. The flow rate is the amount of fuel delivered by the fuel dispenser 32, as measured by the fuel flow meter 32, over the period of time that the fuel was flowing. For example, if a fuel dispenser 32 delivers ten gallons of fuel to a vehicle in a two minute dispensing transaction, the flow rate of the fuel dispenser 32 is five gallons per minute. The fuel dispenser 32 may determine the flow rate by dividing the volume of fuel dispensed, as measured by the fuel flow meter 52, by time, or the flow rate may be determined manually by dividing the volume of fuel delivered as indicated by the fuel dispenser 32 volume display by time. However, with these techniques, several issues can occur which will inaccurately reduce the measured flow rate from the true maximum flow rate capability of the fuel dispenser 32. For example, the nozzle may not be fully engaged during the entire dispensing event thereby reducing the volume throughput and also the calculated flow rate. If the fuel dispenser 32 were to start a timer when performing a flow rate calculation based on the activation and deactivation of the fuel dispenser 32, the timer may start before fuel flow begins thereby causing the time factor in the flow rate calculation to include what is known as “dead time.”
FIG. 4 illustrates an example of a typical dispenser fueling transaction event or more simply called “dispensing event” at a fuel dispenser 32 showing volume of fuel dispensed versus time to illustrate the concept of “dead time.” At the beginning of a dispensing event, labeled as “Dispense Start”, the customer has initiated a dispensing event at a fuel dispenser 32, but has not yet engaged the nozzle 60 handle. The customer may begin a dispensing event by lifting a nozzle 60 holder lift (not shown) on the fuel dispenser 32 or by pressing a button. After the customer begins the dispensing event, the tank monitor 36 and/or site controller 26 receives the “Dispense Start” message that indicates the dispensing event start time and fueling point number or name. After “Dispense Start” and before the nozzle 60 handle is engaged to begin fuel flow, time passes for the dispensing event even though fueling is not yet occurring. Once the customer engages the nozzle 60, fuel flow begins which is labeled as “Flow Start” in FIG. 4. Dispensing “Flow Start” information is typically not made available to the tank monitor 36, the site controller 26, and/or another control system. The time between the “Dispense Start” and the “Flow Start” is known as “dead time,” where fuel is not flowing even though the dispensing event is active at the fuel dispenser 32. After “Flow Start,” fueling occurs and the customer may even discontinue fueling during this period of time on purpose or because of a nozzle 60 snap also causing “dead time” in the middle of a dispensing event, which is not illustrated in FIG. 4. The customer may reduce the rate of fueling by not fully engaging the nozzle 60 handle or a pre-pay transaction may cause automatic slow down of the rate at the end of fueling, which are not “dead time” since some fuel is flowing, but these also cause the flow rate of the fuel dispenser 32 to be reduced from its maximum flow rate.
When the customer desires to end the dispensing event, the customer will disengage the nozzle 60 handle (labeled as “Flow End”) and then deactivate the fuel dispenser 32. This deactivation causes a “Dispense End” message to occur. This message is received by the tank monitor 36, the site controller 26, and/or another control system, and indicates the ending time of the dispensing event, the fueling point number or name, and the total amount and/or running totalizer amount of fuel dispensed. The time between disengaging the nozzle 60 handle and deactivating the fuel dispenser 32 is also “dead time.” As you can see in FIG. 4, the flow rate of the fuel dispenser 32 as measured using the “Dispense Start” and “Dispense End” messages will be lower than the actual flow rates that occur between “Flow Start” and “Flow End” times due to the dead time and due to any discontinuing or reduced engaging of the nozzle 60 handle by the customer or automatically reduced flow during the dispensing event. Therefore, it is not possible to ensure that a reduced flow rate measured using the “Dispense Start” and “Dispense End” messages is caused by a blockage in the fuel supply piping 47 or a problem in performance with a fuel pump, rather than such reduced flow rate, as measured, occurring as a result of dead time during a dispensing event by any or all of the aforementioned causes
FIG. 5 further illustrates the fact that the flow rates as determined using “Dispense Start” and “Dispense End” messages from the fuel dispenser 32 cannot be used effectively to measure the performance of the fuel dispenser 32 to determine if a blockage or performance problem exists. As illustrated in FIG. 5, 1,259 dispensing events were monitored for a fuel dispenser 32 that had no known blockages or performance problems over a sixteen-day period. This monitoring consisted of determining the flow rate in gallons per minute (GPM) using the “Dispense Start” and “Dispense Ends” events for each of the 1,259 dispensing events Each dot in the table illustrated in FIG. 5 represents a single flow rate measurement for the fuel dispenser 32. As can easily been seen from FIG. 5, the flow rates of the fuel dispenser 32 ranged from less than 1 GPM to over 8 GPM, and the flow rates were fairly evenly distributed between these two outer boundaries. Therefore, it is impossible to determine if a blockage and/or performance issue exists at a fuel dispenser 32 from using a flow rate calculation as illustrated in FIG. 5 since a full range of flow rates is possible for a correctly operating fuel dispenser 32.
Therefore, there exists a need to determine if a fuel dispenser 32 has a performance and/or blockage issue that is preventing the fuel dispenser 32 from dispensing the maximum flow rate possible even though the commonly available information from a dispensing event messages includes dead time and/or time of purposefully reduced dispensing flow rates.